This invention relates to an epoxy resin composition for in situ rehabilitation of pipes. In a specific aspect, the invention relates to an epoxy resin/curing agent composition suitable for use in the rehabilitation of pipes which carry high-temperature fluids.
Underground fluid-transporting pipes fracture and corrode with use and age. Repair of a leaking pipe can involve time-consuming and expensive excavation and replacement of the damaged pipe. Excavation of a length of pipe is particularly difficult if the pipe is located in areas where the ground is frozen for long periods of time or if the pipe is located directly beneath a highway or large structure. Techniques have been developed for repairing underground pipe without excavation. These techniques generally involve the saturation of a liner with a thermosettable resin, placement of the saturated liner against the inner surface of the pipe, and cure of the resin to form a hard inner pipe within and adhering to the original pipe.
Both polyester resins and epoxy resins have been used in such in situ pipe rehabilitation processes. Epoxy resins have the advantage of being less susceptible to shrinkage during the cure process. An epoxy resin formulation used in such a process must meet very demanding requirements in addition to resistance to shrinkage with cure. The curing agent used in the formulation must not be water-sensitive, as water is usually present in the pipe or the exterior environment, and the system must not generate so much heat during the cure process as to embrittle or burn the cured resin. Epoxy formulations containing curing agents have been developed which overcome such problems inherent in in situ pipe rehabilitation. However, such systems are not adequate, and may degrade, for repairing pipelines which transport fluids at temperatures above about 65.degree. C., such as hot water or hot process chemicals.
It is therefore an object of the invention to provide an epoxy-based formulation for in situ rehabilitation of pipelines in service at elevated temperatures and/or under corrosive conditions.